Just over two-thirds, (67%) of Thornleigh residents were born in Australia, the national average of 70%; another 4.4% came from England, 3.1% from China and 2.9% from India. However, only 26% identify their ancestry as Australian, which is the largest group; the next most common self-identified ancestries were English 24.1%, Irish 7.6%, Chinese 6.4% and Scottish 6.3%. Nearly three-quarters (74%) of people only spoke English at home; other languages spoken at home included Arabic 3.8%, Mandarin 3.4%, Cantonese 2.7%, Korean 1.3% and Hindi 1.3%.